Currently, digital camera modules are included as a feature in a wide variety of portable electronic devices. Most portable electronic devices are becoming progressively more miniaturized over time, and digital camera modules are correspondingly becoming smaller and smaller. Nevertheless, in spite of the small size of a contemporary digital camera module, consumers still demand excellent imaging. The image quality of a digital camera is mainly dependent upon the optical elements of the digital camera module.
Aspheric lenses are very important elements in the digital camera module. An aspheric lens can easily focus an image on an imaging point, because the aspheric lens can attain different refractive index by means of selected different materials and profiles. Therefore an aspheric lens can avoid many of the image-forming problems of spherical lenses. In addition, with a single aspheric lens, the number of lens pieces in the camera can be reduced. Thus the cameras can have reduced size. Two or more aspheric lenses are used in some cameras for high quality image forming. Contemporary aspheric lenses are made of plastic or glass. Glass aspheric lenses are generally manufactured by way of glass molding. A glass molding machine operates at a high temperature and high pressure during the glass molding process. Therefore the cost of glass aspheric lenses is relatively high. Plastic aspheric lenses are generally manufactured by way of injection molding. Though the cost of plastic aspheric lenses is relatively low, the plastic aspheric lens has low image-forming quality compared to a glass aspheric lens. This is because the transparency of the plastic is lower than that of glass.
What is needed is an inexpensive aspheric lens which provides high image-forming quality in camera.